1. Field of the Invention
The present invention relates to a method of, and an apparatus for, sewing a slide fastener to a pair of fabric pieces, such as, for example, of a curtain, a tent or a lady's dress. It relates to the field of copending application for U.S. patent, Ser. No. 535,729 filed Sept. 26, 1983, now U.S. Pat. No. 4,497,270, dated Feb. 5, 1985.
2. Description of the Prior Art
As shown in FIGS. 1 and 2 of the accompanying drawings, a concealed slide fastener 1 comprises a pair of fastener stringers 4, 4, each stringer including a stringer tape 2 having an inner longitudinal edge folded on itself supporting a row of coupling elements 3 attached to the tape edge. The opposed rows of coupling elements 3, 3 are brought into and out of intermeshing engagement by a slider 5 which is slidably mounted on the rows of coupling elements 3, 3. The slider 5 has a slider body disposed on the coupling-element side of the concealed slide fastener 1 and a pull tab 6 pivotally connected to the slider body and projecting therefrom through the seam-like junction between the folded edges of the opposed stringer tapes 2,2.
Conventionally, for attaching the concealed slide fastener 1 to a pair of fabric pieces 7,7 (FIG. 3), on a sewing machine, the slider 5 is moved on the rows of coupling elements 3, 3 to a bottom end stop (not shown) to uncouple the opposed stringers 4,4 except at their bottom end portions. The uncoupled stringers 4, 4 are simultaneously sewn to the respective fabric pieces 7, 7 with sewn stitches 12, 12 along a pair of folding lines of the respective stringer tapes 2,2 as shown in FIG. 3. At that time, the folded tape edge of each stringer 4 is unfolded until the coupling elements 3 are erected with their head portions 10 directed downwardly, and the coupling elements 3 and the element-supporting tape edge of each stringer 4 are slidably received in a respective one of a pair of parallel downwardly opening grooves 8,8 in a presser foot 9 of the sewing machine. A pair of parallel sewing needles 11,11 are reciprocable through a pair of vertical holes in the presser foot 9. Also, during this sewing, the two stringers 4, 4 are superimposed over the respective fabric pieces 7,7 in such a manner that initially-outer (as seen in FIGS. 1 and 2) longitudinal edges of the opposed stringer tapes 2,2 are directed inwardly, i.e. toward each other.
This sewing operation is continued until the sewing stiches 12, 12 reach a position immediately short of the slider 5 disposed adjacent to the bottom end stop (not shown) of the slide fastener 1. As a result, the two stringers 4, 4 have been sewn to the respective fabric pieces 7,7 leaving the lower end portions of the stringers 4, 4 not sewn and hence floating from the fabric pieces 7,7.
As shown in FIGS. 4, 5 and 6, the sewn fabric pieces 7,7 are folded back on themselves about the sewn stiches 12, 12 as the two stringers 4,4 are progressively coupled together by moving the slider 5 from the bottom end stop (not shown) to a pair of top end stops (not shown) to close the concealed slide fastener 1. At that time, in order for their correct coupling, the two stringers 4, 4 need to assume proper twisted positions that are in mirror symmetry (FIG. 5).
Practically, however, because the lower end portion of the sewn slide fastener 1 is not sewn and hence floating from the fabric pieces 7,7, the opposed stringers 4,4 would tend to assume an improper twisted position that is not in mirror symmetry (FIG. 7), thus causing portions of the fabric pieces 7,7 to bulge inwardly between the two stringers 4,4 (FIG. 8). The bulged portions of the fabric pieces 7,7, can be caught by the slider 5 during the coupling of the two stringers 4,4; in such occurrence, the coupling of the two stringers 4,4 must be restarted after removing the caught fabric pieces 7,7 from the slider 5, which is laborious, time-consuming, and annoying.
Accordingly, this conventional method causes problems in the case where a plurality of the concealed slide fasteners 1 are successively sewn to successive pairs of the fabric pieces 7,7 and in which the sewn concealed slide fasteners 1 are temporarily stacked and are then supplied one after another to a finishing station where the opposed stringers 4,4 of each concealed slide fastener 1 are coupled by moving the slider 5.